The sons of Shiva and parvati were called Ganesha and kartikeya; both are equally dear of them. Once it happened that devas gave one divine fruit to Shiva and parvati and told them that it is a special fruit. Whoever eats it, will get the supreme knowledge but both the sons want to eat it. So this leads to be argument between them. So in that situation Shiva told that whoever will circle the world three times and come back first will get the fruit.
Kartikeya got on the peacock, his vahana, and flew around the world stopping at all the sacred stops on the way and offering his prayers. Ganesha knew that with his huge belly and slow moving mouse he cannot defeat his elder brother kartikeya. But Ganesha was talented and started circling around his parents three times. Shiva and parvati asked him “what are you doing?” Ganesha replied that his parents are the whole world for him. He was not using any other logic to win the race. Ganesha really loves his parents. So in last Ganesha got the blessings of his parents and won the divine fruit.
When kartikeya came back, he didn’t like the argument and felt cheated. He asked his parents that how Ganesha could win. Then Shiva and parvati explained that Ganesha went around us and he said, “Father is sky and mother is earth for their children”.